The object of the invention is a light source.
The object of the invention is also a light-source band.
The invention relates to light sources generally, more particularly to LED light sources. The invention also relates to light-source bands, which are used generally in control systems, guidance systems and warning systems.
Light sources, e.g. LED light sources, are typically protected with various plastic materials, such as with silicon. It has been observed that the materials used nowadays, from which elasticity is also required, are sensitive to UV light and/or to heat. This often results in deterioration of the clarity and/or transparency of the protective material, sometimes very quickly, and at the same time in a deterioration in the luminescent capability of the light source. Often an undesired effect appears as a yellowing or as a stronger coloring of the protective material and as a deterioration in transparency.
The drawback is typical e.g. in connection with LED light sources producing white or blue light, in the range of effect of which a darkening of the protective material and thus a deterioration in transparency have been observed.
The drawback mainly appears in connection with LED light sources, the wavelength of which is short and mainly UV light, i.e. mainly with blue and white LEDs. The problem is thus the darkening of the protective plastic occurring from the combined effect of UV and heat, e.g. the heat produced by a LED light source. Another drawback is also the impurity that gains access to the surface of a LED light source via diffusion for the aforementioned reasons, which darkens the surface of the LED circuit.
Earlier an epoxy resin type of protective agent was used in the protection inside the enclosure of a LED light source, but there has been a shift to the use of silicon resin in the high bright components available nowadays. This has been assumed to improve the lifetime of LED luminaires, but at the same time it has enabled detrimental characteristics, such as the diffusion of substances, when the temperature achieved by a light source is higher than in conventional LEDs of lower intensity. An obstacle to the use of epoxy in these cases has been exactly those same problems, the changing of the color of the protective material. Silicon, for its part, is also soft and does not give very good mechanical protection, and is not as such good protection against damp in demanding conditions.
The drawbacks of prior art are substantial, e.g. in connection with LED light-source bands, which have as protection a flexible transparent protective envelope. LED light-source bands can be used e.g. in connection with various systems, such as for guiding people in situations of danger, such as in fire situations, to the emergency exits of buildings or vessels. These are various lightings for emergency exits. Known in the art are guidance lights, in which light sources are fixed consecutively into the shape of a band. The light sources of the band are arranged to light up in a situation of danger and to illuminate the emergency exit. Darkening of the plastic material functioning as protective material, however, impairs the brightness of the light sources, which is a great drawback e.g. in fire situations, in which visibility can otherwise be poor e.g. owing to the formation of smoke.
The aim of the present invention is to achieve an entirely new type of solution for a LED luminaire, by means of which solution the drawbacks of prior art solutions are avoided. Another aim is to achieve a LED light-source band, the clarity and/or transparency of the protective material of which remain good.